July 4th, 2011
Meta-Analysis: Increased CV Risk Associated with Varenicline (Chantix)
The anti-smoking drug varenicline (Chantix, Pfizer) is associated with an increased risk for serious adverse cardiovascular events, according to a new meta-analysis published in CMAJ.
In the meta-analysis, Sonal Singh and colleagues analyzed data from 14 double-blind randomized trials involving 8216 subjects. The rate of serious adverse cardiovascular events was 1.06% (52/4908) among varenicline recipients versus 0.82% (27/3308) among placebo recipients (odds ratio, 1.72; 95% CI, 1.09-2.71). The authors, led by Curt Furberg, estimated that the number needed to treat with varenicline for one additional person to successfully quit smoking was 10, whereas the number needed to cause one additional serious CV event was 28. The authors also noted that varenicline already has a black box warning about adverse neuropsychiatric symptoms.
In an associated commentary, J. Taylor Hays, who has conducted research on varenicline with funding from Pfizer, writes that “the small absolute risk of cardiovascular events associated with varenicline treatment is outweighed by the enormous benefit for reducing cardiovascular morbidity and mortality that can be achieved with successful smoking abstinence.”
The CMAJ paper follows a statement issued by the FDA on June 16, which warned that the drug might increase the risk for cardiovascular events in people who already have cardiovascular disease. “This would have raised a red flag for us if the flag hadn’t already been flying,” said the FDA’s Celia Winchell, in an interview with the New York Times.
The Times also quoted Furberg, who has served as an expert witness in cases against Pfizer: “We have known for many years that Chantix is one of the most harmful prescription drugs on the U.S. market, based on the number of serious adverse effects reported to the FDA. It causes loss of consciousness, visual disturbances, suicides, violence, depression and worsening of diabetes. To this list we now can add serious cardiovascular events.”
In a press release, Pfizer said that the meta-analysis was unreliable and that “the currently available safety data on Chantix… do not support an increased cardiovascular risk associated with Chantix.”